Emergency Service Identifiers

1
Emergency Service Identifiers

• Presented by Henning Schulzrinne
• Columbia University
• hgs_at_cs.columbia.edu

2
Service URN

• Idea Identifiers to denote emergency calls
• and other generic (communication) services
• Described in draft-ietf-ecrit-service-urn-05.txt
  (passed WGLC sent to the IESG)
• Document defines the following emergency service
  identifiers
• sos General emergency
  services
• sos.animal-control Animal control
• sos.fire Fire service
• sos.gas Gas leaks and gas
  emergencies
• sos.marine Maritime search and rescue
• sos.mountain Mountain rescue
• sos.physician Physician referral service
• sos.poison Poison control center
• sos.police Police, law enforcement

3
counseling services
4
Services under discussion

• 211 (social service referral), 311
  (non-emergency government services)
• Emergency services (first responders)
• used by PSAP, not civilians
• e.g., urnserviceespolice
• Non-emergency commercial services
• urnservicerestaurant.italian
• urnservicetransportation.taxi

5
UA recognition UA resolution
location information
mapping
mapping may recurse
DHCP LLDP-MED
9-1-1 (dial string)
leonianj.gov
INVITE urnservicesos To urnservicesos Route
sipfire_at_leonianj.gov ltlocationgt
INVITE urnservicesos To urnservicesos Route
sippsap_at_leonianj.gov ltlocationgt
identification TBD
6
UA recognition proxy resolution
mapping
9-1-1
(outbound proxy) provider.com
INVITE urnservicesos To urnservicesos ltlocat
iongt
INVITE urnservicesos To urnservicesos Route
sippsap_at_leonianj.gov ltlocationgt
7
UA recognition proxy resolution(proxy location
determination)
mapping
9-1-1
provider.com
INVITE sippsap_at_leonianj.gov To
urnservicesos Geolocation ltlocationgt
INVITE urnservicesos To urnservicesos
8
Proxy recognition proxy resolution
mapping
9-1-1
provider.com
INVITE urnservicesos To sip911_at_provider.comus
erphone Geolocation ltlocationgt Route
sippsap_at_leonianj.gov
INVITE sip911_at_provider.comuserphone To
sip911_at_provider.comuserphone
9
Labeling requirements

• Needs to work even if UAC does not recognize
  emergency call
• Needs to survice multiple mappings
• e.g., country ? state ? county
• Needs to play nice with SIP routing architecture
• e.g., pre-loaded service routes

10
Alternatives considered

• only trust Accept-Contact from same trust domain
• see P-Asserted-Identity model (RFC 3325) ?
  brittle
• or use Identity model ? signed by outbound proxy
• unfortunately, not covered by
• doesnt help with UA rec/res model!
• creating a new header likely to have similar
  issues
• re-do mapping and ensure that URL matches
• server can learn list of legal URLs after a
  while
• can fail if mapping is dynamic (advertisement
  changes)
• then just replaces URL
• forces each outbound proxy to do mapping

• check external source that URL is indeed a PSAP
• use draft-ietf-sipping-certs for destination URL,
  but would need to have a role-based cert this is
  a bona-fide PSAP
• easy to posit, harder to deploy globally
• can incur significant delay
• but only needed when theres service
  differentiation
• new TLD for PSAPs only ?

11
References and contact info

• IETF ECRIT Working Group
• http//www.ietf.org/html.charters/ecrit-charter.ht
  ml
• Service URN IETF Draft
• http//tools.ietf.org/wg/ecrit/draft-ietf-ecrit-se
  rvice-urn/